1. Field of the Invention
The present invention relates to a new and improved anchor apparatus and method for orthodontic appliances and, more particularly, to such an anchor apparatus and method wherein different anchor devices are used for different areas of the mouth to ensure adequate lateral and longitudinal support in each area of the mouth.
2. Description of the Background Art
In the current state of the art, self-tapping and standard bone screws of a common construction are used in all areas of the mouth for anchoring orthodontic appliances or the like. These screw constructions are prone to failure or movement owing to the thin cortical bone in some portions of the mouth. Differences in the bone structure and in the covering tissue complicate usage of a common screw construction for all areas of the mouth. For example, there is a need for a thin anchor in the incisal mouth area to avoid root contact and to allow for installation close to a tooth. Also, in the zygomatic process of the maxillary bone, the surrounding tissue often is deeper than the head of the typical bone screw, thereby making it difficult to attach a ligature or other retaining device to the bone screw.
In most cases, interference fit nut drivers are used to prevent the screw from dropping into the mouth. Such nut drivers must often be wiggled from side to side for release with the possibility of unseating the screw during the process. Also, the interference fit is not a 100% reliable solution to preventing the screw from dropping into a patient's mouth with the potential of it being swallowed and requiring hospitalization for removal.
A further disadvantage of existing bone screw constructions are that they have no radial support and thus rely on the support of the screw threads alone in the perpendicular access of installation. Accordingly, such screw constructions are subject to failure or movement when subjected to lateral or radial forces.
There is a need, therefore, for a new and improved anchor apparatus and method for orthodontic appliances which insures that the anchor or bone screws are firmly seated in different areas of the mouth and are not subject to failure or movement when subjected to lateral forces. There is also a need for an anchor apparatus and method that prevents an anchor screw from being unseated during the installation process and dropping into a patient's mouth. The new and improved anchor apparatus and method of the present invention fills this need.